This center grant supports a clinical and laboratory program for a 20-bed intensive care ward devoted primarily to the treatment of hematologic malignancies by marrow transplantation. Total body irradiation and/or high dose chemotherapy is utilized to condition the patients to accept the graft and to eliminate malignant cell populations. Supportive facilities include granulocyte and platelet transfusions, laminar air flow isolation, gut sterilization and sterile diets. Immunologic recovery is monitored with long term followups. Supporting laboratories provide information in areas of pathology, virology, microbiology, hematology, cryobiology, cytogenetics and histocompatibility typing. Extension of the marrow grafting program to treatment of solid tumors is proposed. Research areas include prevention and treatment of graft versus host disease, opportunistic infections, acceleration of immunologic recovery, prevention of recurrent leukemia, application of immunotherapy to antileukemic treatment, in vitro assays of hematopoiesis, granulocyte transfusion techniques and their efficacy and studies of histocompatibility in marrow transplantation. Data processing and biostatistic functions provide maximum utilization of information generated.